a)
\(\sqrt[3]{27}-\sqrt[3]{-8}-\sqrt[3]{125}=\sqrt[3]{3^3}-\sqrt[3]{(-2)^3}-\sqrt[3]{5^3}\)
\(=3-(-2)-5\)
\(=3+2-5=0\).
b)
\(\dfrac{\sqrt[3]{135}}{\sqrt[3]{5}}-\sqrt[3]{54}.\sqrt[3]{4}=\dfrac{\sqrt[3]{27.5}}{\sqrt[3]{5}}-\sqrt[3]{54.4}\)
\(=\dfrac{\sqrt[3]{5}.\sqrt[3]{27}}{\sqrt[3]{5}}-\sqrt[3]{216}\)
\(=\sqrt[3]{27}-\sqrt[3]{216}\)
\(=\sqrt[3]{3^3}-\sqrt[3]{6^3}\)
\(=3-6=-3\).
